Cryptography is the practice of establishing a secure connection between two parties in the presence of a third party whom you don't want to be able to read your messages.

Cryptographers design algorithms and protocols, which do exactly this (and many other things). They also use a lot of time looking for security holes in existing protocols to make sure they can still be trusted. This is called cryptanalysis.

We have a very important rule on this subreddit, we won't solve your ciphers unless you provide us with an algorithm. If anyone sends you a code or a cipher without telling you how they encrypted, don't bother posting it on this subreddit - your post will get deleted. We redirect you to /r/breakmycode or /r/codes. Thank you for your understanding and for following the rules.